Armor plate quenching



J c. E. SORENSEN ETAL 2,378,044

ARMOR PLATE QUENGHING Filed May 17, 1943 N Q M [Q m m mam.

.. Patented June 12, 1945 UNITED STATES; PATENT OFFICE"samoarmraqnnncnmo Charles E. Sorensen, Detroit, and Russell H. Me-Carroll and Nicholas E. Bothenthaler, Dearborn, Mich., assignors to FordMotor Company, Dearborn, Mich, a corporation of Delaware ApplicationMay, 1943, Serial No. 487,276 2 Claims. (01. ass-e) This inventionconcerns metal processing and, more particularly, a method ofstraightening and heat-treating armor and other large plates utilizing aspray quench.

This invention concerns the heat-treatment of thick metal plates and isparticularly directed to apparatus by means of which such plates may bequenched without warping. For a more complete description of theproblems and difllculties encountered in this work, attention isdirected to copending application Serial No. 454,576, of which this is acontinuation in part.

The present invention comprises the use of Pressure platens in which themetal treated can be subjected to initial pressure and means by whicha-coolant may be uniformly directed over the surface of metal so held toefiect the desired heat-treatment. In the earlier application referredto, the quench was obtained by circulating coolant in conduits withinpress platens proper and thus cooling the platen surfaces to a point atwhich the desired cooling effect on the work was obtained. This has manyadvantages, particularly with the lighter plate, and results in workwhich is warp free and properly quenched. However, when used with aheavier plate, the pressure required is excessive and the amount of heatwhich must be removed in a short time to obtain the desired hardening,is beyond the capacity of the coolant. Nevertheless, the basic principleof first subjecting the work to be heat-treated to sufiicient pressureto straighten it and to prevent its warping and then instantaneouslyquenching it while held in that position, is used in the present case aswell. An advantage over the present one is thatit permits theheat-treatment of a heavier armor plate and yet effects a very sharpcore quench to obtain the core hardness required for ordnance work.Other advantages reside in the lower press capacity required, the lowercost of the platens required, and the increased speed at which theoperation can be carried out.

With these and other objects in view, the invention consists inthearrangement, construction and combination of various parts of theimproved device, expressed in the specification, claimed in the claims,and illustrated in the accompanying drawing in which:

Figure '1 is an elevation of one form of press and platens used in theinvention, a portion thereof being in section.

Figure 3 is a plan view, on an enlarged scale, of one of the platens, aportion of'the surface being removed to show the underlying fluid connections.

Referring now to Figure -1, a typical press 9 is shown set up topractice this invention, the press mechanism itself not being shown indetail since it may be of any conventional form. Reference character Illrepresents the plate to be straightened and quenched resting on thelower platen 'I] which overlies the coolant-distributing section .12,both of them being secured to the bed l3 of the press 9. The upperplaten M, of identical structure and .equipped with similar facilitiesfor coolant distribution, is secured to the head IS. A spray shield l6surrounds and moves with the head is and the gutter ll, equipped'withthe outlet pipe I8, is secured to the bed I3. I An automatic limitswitch 35 having an extending actuating arm 36 and roller 31 is mountedon the upper face of the platen II in such a position that the rollermay engage the work Ill. The limit switch is set so that when the workis forced into contact with the lower bosses la, the valve 38 in thesupply line 39 leading to the intake pipe 21 is automatically openedthrough the circuit indicated at 40 supplying quenching fluid.

Each platen, H or M, is formed of cast iron and has a number of bossesl9 projecting from the surface in a substantially regular pattern (asbest seen in Figure 3), these bosses having a working face 20 andcommunicate through a hollow center 2| with the bottom of the platen. Inaddition, a plurality of spray holes 22 is drilled through the materialof the boss from points adjacent the-working face to the hollow center 2I. The distributing plate, also of cast iron, has a number ofintersecti'ngchannels 23 formed on its upper surface which are incommunication Figure 2 is a view, on an enlarged scale, of a withtransverse headers 24, which in turn communicate by the leads 25fand thesupply line 26 with the intake pipe 21 which runs the length of thepress. The points of intersection 28 of the channels 23 on section l2,correspond with the location of the bosses IS on the platen H sothat aplurality of channels is provided in every instance for fluid flow toeach boss.

A number of rollers 29 is secured to auxiliary bosses 32 spaced atintervals on the platen II by means of spring arms 30 which aresufficiently strong to support the work above the bosses during feedingand removal, but which are depressed when the working pressure isapplied to the plate. The rollers are maintained in alignment by therigid rel-rs u The coolant is fed through the head is and bed I! of thepress to the intake pipe 21. then through the supply pipes It, leads 2!and transverse headers 24 in the distributing section II to the channels2! from which it is fed to the bosses I9 and sprayed against the surfaceof the plate It through spray holes 22. The sprayed coolant drains fromthe upper surface of the plate In and from the lower platen ii to thegutter II from which it flows to the outlet pipe it. As was the case inthe prior application, the flow of the coolant through the platens isstrictly regulated to obtain a sumciently high velocity to avoid theformation of steam pockets. although the danger of this occurring isconsiderably less in the present instance than in the former where theentire surface of the platen was in direct contact with the work.

In operation, the press is opened; the plate It is rolled into positionon the rollers 18; the press head I is brought down into engagement withwork depressing the rollers so that the bosses I! on the upper and lowerplatens bear directly against the work; suitable pressure is appliedand, simultaneously, a quenching spray of coolant impinges on the platefrom the numerous spray holes in the bosses. This quenches the plate tothe desired core hardness and at the same time warpage or deformation isprevented by means of the pressure applied through the platens.

The principal advantage of this invention is that heavier plates may behandled and restrained from warpage by presses oisubstantialiy lowercapacity than those required when a solid platen is used. At the sametime a superior quenching effect is obtained because of the volume orcoolant that can be brought into instantaneous contact with the heatedsurface and as quickly removed to permit continuous coolant circulationby the spray. The flow of coolant through the bosses ll cools theirworking surface sothat the area of immediate contact (if properlyproportioned) between the bosses l9 and plate It is quenched atapproximately the same rate as the portion of plate exposed to thespray.

In the preferred form, the total working race area of the bosses shouldbe 10 per cent of the platen area and not less than five or more than 15per cent of that area. The diameter of the individual boss should not bein excess of twice the thickness of the plate to be worked on. A spacingchosen in these ranges of total area and of individual boss diameters isadequate to support the plate against warpage and while the bosspressure is high, the over-all pressure and the required press capacityare low. As a comparison, a 700- ton pressure is required inspray-quenching a standard armor plate while with the internally cooledplaten, at least 2,400 tons is required for the same size plate. Thespray-quenching platen has been found to have a longer life, for thisamong other reasons, than the internally cooled platen and this is aconsiderable item when the size of the work treated is noted. The quenchobtained with the spray is slightly faster than that obtainable with thebest platen practice so aavaou.

that a somewhat higher Brinell may be obtained,

although the results from the platen are, in general, satisfactory formost requirements. Great care must be taken to have the internallycooled platen, when used, absolutely flat to give uniform pressure andto prevent water from standing on it, for if the latter occurs when theplate is brought into position, the plate areas adjacent this standingwater will be initially surface quenched and the metallurgicalcharacteristics of the plate will vary. Using spray quenching, the areaof the bosses (about -10 per cent, as explained above) is so small thatit is not difficult to keep them flat and dry, and even if some of themdo retain a surface film of water the amount is so small that thequenching effect is practically nil. Though some scaling does occur, thespray is so rapid that the thickness of the scale is not objectionableand it is loose and readily removable. Since the water in contact withthe quenching fluid is circulated around the plate with great rapidity,the quenching time is small, as compared with other quenching methods,two and a half minutes at the most being required to quench a diflicultplate from the furnace temperature of 1,650 F.

Some changes may be made in the arrangement, construction andcombination of the various parts of the improved device and of the stepsof the improved method without departing from the spirit of theinvention and it is the intention to cover by the claims, such changesas may reasonably be included within the scope thereof.

The invention claimed is:

1. In a metal-working press adapted for straightening and quenchingoperations on armor and other like plate of substantial thickness, abed, a platen secured thereto, a head, a second platen secured thereto,projecting bosses having flat working faces arranged in juxtaposition on40 the opposed faces of said platens, said bosses being hollow andhaving nozzles formed therein adjacent the working faces thereof,coolant fluid connections including a valve leading to said bosses, andmeans for simultaneously actuating said valve and said platens toproject coolant fluid from said bosses when said bosses compressivelyengage the workpiece.

2. In a metal-working press adapted for straightening and quenchingoperations on armor and other like plate of substantial thickness, abed, a platen on said bed, a head, a second platen carriedby said head,a plurality of projecting bosses having substantially flat working facesarranged on the opposed faces of said platens, said bosses being hollowand having nozzles formed therein adjacent the working faces thereof,coolant fiuid connections including a valve to the interior of saidbosses means for simultaneously actuating the valve and said platens toproject coolant fluid from said bosses when said bossescompressively-engage the workpiece and resilient means on said lowerplaten urging such workpiece out of contact with said bosses on saidlower

